Technetium-99m complex of N-(2-pyridylmethyl)iminodiacetic acid as a new renal radiopharmaceutical

A tetradentate chelating agent constituting of an iminodiacetic acid group and a nitrogen atom of pyridine, N-(2-pyridylmethyl)iminodiacetic acid (PMI DA), was coordinated with Tc-99m and evaluated as a renal functional agent. The complex of PMIDA with Tc-99m was prepared by using a stannous chloride solution as a reducing agent. The chelating efficiency was analyzed by thi n layer chromatography and electrophoresis. Chelation with Tc-99m resulted in a single radiochemical product. Biological studies were performed in mic e and rats. Tc-99m-PMIDA was removed from the circulation solely by the kid neys. Clearance of Tc-99m-PMIDA from the blood and the kidneys was as rapid as that of Tc-99m-diethylenetriaminepentaacetic acid. The rate of blood cl earance was unaffected by the administration of probenecid (a test for tubu lar secretion by the weak-acid mechanism), so that the glomerular filtratio n rate could be estimated by measuring its clearance from the blood. The re sults in animals with myohemoglobinuric acute renal failure suggested that Tc-99m-PMIDA might be a useful renal function radiopharmaceutical.